Work machines which utilize a track type drive mechanism have several advantages over wheel type work machines. The tracks give the work machine excellent traction while spreading the weight of the machine over a large area. Thus, the track type work machine has enhanced off road capabilities.
A typical undercarriage of a track type drive mechanism consists of a track made of a number of shoes linked together, a sprocket which drives the track, and a number of rollers which distribute the weight of the work machine along the track.
In a conventional track type drive, a tooth of the sprocket engages a stationary bushing in the shoe of the track. This type of engagement causes considerable wear as the teeth of the sprocket advance the track around the sprocket. A disadvantage to this type of track drive is that the bushings of the track must be replaced as they wear out. Replacing the shoes of the track and the teeth of the sprocket is costly and time consuming.
One method of reducing track wear is to mount a rotating bushing on the shoes of the track type work machine. The rotating bushing eliminates much of the friction between the shoes and the teeth of the drive sprocket as the sprocket engages and disengages the track as the track is advanced around the drive sprocket. Mounting a rotating bushing on the shoe greatly reduces wear on the shoes. A disadvantage of mounting a rotating bushing on each shoe is the cost of the large number (typically 30 to 50) of bushings needed in order to place a bushing on each shoe of the track assembly.
What is needed therefore is an apparatus and method for reducing wear in a track type drive system which overcomes one or more of the above-mentioned drawbacks.